Many animals in nature and at home resting in different ways.Some - standing some - lying or sitting sleep, some - afloat.Here, for example, have you ever thought about how sleeping fish?This cold-blooded too, need to rest, at least short-term.Interesting question, you see, because nobody has ever seen fish with eyes closed.Why is that?Because they do not have eyelids, and they have nothing to close them!
Land animals have to moisturize constantly blinking, ocular surface.And in the dream it is quite difficult to implement, since the control of the reactions is lost.Therefore, the mammalian eye, for example, closed eyelids during sleep.We fish a different story: they exist in water, so moisturize constantly eyeball is not necessary.But they, like all animals, have to rest.To learn how to sleep fish, we will describe in this article.A sleep these representatives of the fauna of the world in different ways, depending on the species and habitats.
Like sleeping fish
known that the fish is not as relaxing as it is done, for example, mammals (well, by the way, to study the behavior of these animals to those who have an aquarium).Dream of fish, most recalls during rest, relax, slow down when many functions of the body, and the reaction is weakened.Some fish are so cut off their reactions that they can literally touch the hands and shine a flashlight into the eyes - still they remain immobilized.Certain types, on the contrary, in this state may well perceive danger.
Where to sleep fish
During his vacation, many of these cold-blooded species are virtually immobile.They usually rest on the bottom area.This applies to many of the major river and lake views.But the assertion that every fish is asleep on the bottom, is not quite true.Some ocean species of fish should be constantly on the move, even during sleep.These include, for example, sharks and tuna.Water must always pass through their gills, or they may suffocate.Therefore tuna lie on the water against the current, and thus, swimming, relaxing.And sharks - these contemporaries of the dinosaurs - and does not bubble, which is present in other species.This fact is one more argument to be in motion even at rest.Because otherwise the shark will simply sink to the bottom and, in the end, as it may sound funny, it sinks!And yet - at the stingrays and sharks there are no caps on the gills, like many bony fish, so the water comes back only at the time when the fish moves, and sleep relatively quiet, as do the bone, they do not work - you need all the timesomewhere to go.
Features repose
So in what position sleep fish depends on the species.For example, Astronotus hanging upside down.A clown fish at the bottom of the tank is placed to the side.Some aquarium fish just hang motionless.
Like sleeping fish?Under natural conditions, the provisions for the rest it can also be very different.Flounder digged in sandy soil at the bottom.Cod lying asleep.Herring - and does belly up, rafting down the river.Most demersal fishes sleep in secluded areas, previously prepared among the rocks and crevices of coral and algae.A parrot fish wraps itself in a cocoon of mucus to become invisible to predators.
duration
How many fish sleep?Most of the fish, as many animals are active during daylight hours.By nightfall, life dies, it's time to rest.Therefore, for example, it is so important for the fish kept in aquariums, reasonable enjoyment of their natural mode.Agree, if you wake at three o'clock in the morning bright light and noise, it is unlikely you will be able to enjoy.And for fish: it is required to turn off the artificial lighting of the aquarium in the evening and at night, the animals were able to relax.Otherwise, it can significantly shorten the life expectancy of aquarium fish.
Night Hunter and sleeping
characteristic that some river predatory fish (such as catfish or eel) do not sleep at night.They prefer to hunt, and in the afternoon - rest.However, among the fish, leading the daily way of life, caught by those who love to organize midday siesta.But dolphins (mammals, previously ranked as fish) does not sleep ever!Hemispheres - left and right - brain of a dolphin resting alternately (each about 6 hours).All the rest of the time awake both hemispheres.
